package org.greenstone.gsdl3.gs3build.metadata;

import java.io.PrintWriter;

import java.util.List;

import java.sql.SQLException;
import java.sql.ResultSet;

import org.greenstone.gsdl3.gs3build.util.GS3SQLConnection;
import org.greenstone.gsdl3.gs3build.database.*;

/**
 *  Implement a single namespace
 */

public abstract class METSNamespace
{
  protected String       type;        // the type of the metadata
  protected String       otherType;   // if a non-standard type, then...
  protected String       name;        // e.g. "DC" for Dublin Core
  protected METSLocation location;    // the location of the corresponding file
  protected String       group;       // the group of metadata namespaces to which
  // this namespace belongs
  protected String       id;          // the ID for this namespace

  public METSNamespace(String name)
  { this.name        = name;
    this.location    = null;
    this.group       = null;
    this.id          = null;
  }

  public METSNamespace(String name, METSLocation location)
  { this.location = location;
    this.name = name;
    this.group       = null;
    this.id          = null;
  }

  /**
   *  Get the name of the namespace...
   *
   *  @return <code>String</code> the name of the namespace
   */
  public String getName()
  { return this.name;
  }

  /**
   *  Get the group of namespaces to which this namespace belongs.
   *
   *  @return <code>String</code> the name of the namespace group
   */
  public String getGroup()
  { return this.group;
  }
	
  /**
   *  Set the group of namespaces to which this namespace belongs.
   *
   *  @param <code>String</code> the name of the namespace group
   */
  public void setGroup(String group)
  { this.group = group;
  }

  /**
   *  Get the ID for this namespace.
   *
   *  @return <code>String</code> the id of the namespace
   */
  public String getID()
  { return this.id;
  }

  /**
   *  Set the id of this namespace.
   *
   *  @param <code>String</code> the name of the namespace group
   */
  public void setID(String id)
  { this.id = id;
  }

  /**
   *  <p>Indicate whether this namespace is open to being changed or not.</p>
   *  <p>Metadata which is created from a distinct file cannot be changed,
   *  only those which have no associated file can be modified.
   *
   *	@return <code>boolean</code> whether this namespace can be altered.
   */
  public boolean isEditable()
  { return (this.location == null);
  }

  public abstract boolean addMetadata(String label, String value);
  public abstract boolean setMetadata(String label, String value);
  public abstract boolean removeMetadata(String label);
  public abstract boolean removeMetadata(String label, String value);
  public abstract List    getMetadata(String label);
  public abstract boolean write(PrintWriter writer);
  //  public abstract boolean writeSQL(GS3SQLConnection connection);

  /**
   *  Write out the metadata to an SQL database through a <code>GS3SQLConnection</code>.
   *
   *  @param <code>GS3SQLConnection</code> the SQL database to use.
   */
  public boolean writeSQL(int parentId, GS3SQLConnection connection)
  { 
    GS3SQLAction action;

    // If the namespace is not null, then set it...
    if (this.id != null) {
      // use an update action in this case...
      GS3SQLUpdate update = new GS3SQLUpdate("namespaces");
      update.addValue("NamespaceID", this.id);

      // set up the where clause
      GS3SQLWhere where = 
	new GS3SQLWhere(new GS3SQLWhereItem("NamespaceRef", "=", this.id, 
					    GS3SQLField.INTEGER_TYPE));
      update.setWhere(where);
      action = update;
    }
    else {
      GS3SQLInsert insert = new GS3SQLInsert("namespaces");
      action = insert;
    }

    if (this.location != null) {
      action.addValue("fileLoc", this.location.getLocation().toString());
      action.addValue("fileType", "URL");
    }
    else {
      // no location stuff
    }
    action.addValue("MetadataRef", Integer.toString(parentId), GS3SQLField.INTEGER_TYPE);
    action.addValue("NamespaceType", this.name);

    // Execute the action
    connection.execute(action.toString());

    // then get the namespace reference number if needsbe...
    if (this.id == null) {
      GS3SQLSelect select = new GS3SQLSelect("namespaces");
      select.addField("NamespaceRef");
      GS3SQLWhereItem whereItem = new GS3SQLWhereItem("MetadataRef", "=", Integer.toString(parentId), GS3SQLField.INTEGER_TYPE);
      GS3SQLWhere where = new GS3SQLWhere(whereItem);
      whereItem = new GS3SQLWhereItem("NamespaceType", "=", this.name);
      where.add(where);
      try {
	connection.execute(select.toString());
      
	ResultSet result = connection.getResultSet();
	result.last();
	this.id = Integer.toString(result.getInt("NamespaceRef"));
      }
      catch (SQLException sqlex)
      { this.id = null;
        System.err.println(sqlex);
	return false;
      }
    }

    return true;
  }

  public static METSNamespace readSQL(GS3SQLConnection connection, ResultSet resultSet)
  {
    METSLocation metsLocation = null;
    
    try {
      String name = resultSet.getString("NamespaceType");
      String id = resultSet.getString("NamespaceRef");
      String location = resultSet.getString("fileLoc");
      String type = resultSet.getString("fileType");
      if (location != null && type != null) {
	metsLocation = new METSLocation(type, location);
      }

      METSNamespace namespace = NamespaceFactory.initNamespace(name, metsLocation);
      namespace.id = id;

      int namespaceRef = resultSet.getInt("NamespaceRef");
      
      GS3SQLSelect select = new GS3SQLSelect("mdvalues");
      select.addField("*");
      GS3SQLWhere where = new GS3SQLWhere(new GS3SQLWhereItem("NamespaceRef", "=", Integer.toString(namespaceRef),
							      GS3SQLField.INTEGER_TYPE));
      select.setWhere(where);

      connection.execute(select.toString());
      
      ResultSet valuesSet = connection.getResultSet();
      if (valuesSet != null && valuesSet.first()) {
	do {
	  String label = valuesSet.getString("label");
	  String value = valuesSet.getString("value");

	  namespace.addMetadata(label, value);
	}
	while (valuesSet.next());
      }

      return namespace;
    }
    catch (java.net.MalformedURLException urlEx)
    { System.out.println(urlEx);
    }
    catch (SQLException sqlEx)
    { System.out.println(sqlEx);
    }    
    return null;
  }
}